JPH07154983A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent a compressor from overheating by a method wherein, when the compressor is started, only the generation-stop-current level of an inverter output frequency is made valid so as to avoid a wasteful current flow. CONSTITUTION:When a compressor is started and a target output frequency >=a prescribed frequency Ft, an output frequency is raised from the start of the compressor. Until the output frequency reaches the prescribed frequency Ft, only the generation-stop-current level It of the output frequency is made valid, and a detection current signal Io is compared with only the generation- stop-current level It. That is to say, when the target output frequency coincides with the output frequency, the frequency is held. When the target output frequency does not coincide with the output frequency, the frequency is raised or lowered. Thereby, a wasteful current does not continue to flow, and it is possible to prevent the compressor from overheating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner which drives a compressor by an inverter device.

[0002]

2. Description of the Related Art In a conventional air conditioner, for example, an indoor heat exchanger and an indoor blower are arranged indoors, and an outdoor heat exchanger, a compressor and an outdoor blower are arranged outdoors.

Generally, a conventional inverter device for an air conditioner is constructed as a load reducing means as shown in FIG. That is, the arithmetic / control circuit 5 which has received the command signal
Calculates an appropriate target output frequency, and drives circuit 4,
The compressor 3 is driven by the semiconductor switching element group 2.

At this time, the arithmetic / control circuit 5 controls the output frequency of the drive circuit 4 based on the detected current signal Io from the current detector 6 which detects the inverter input current.

An example of controlling the output frequency is shown in FIG.

The output frequency stop current level It, the output frequency decrease current level Id, and the output frequency increase stop current level Is are set in advance in the arithmetic / control circuit 5, and during the operation of the compressor, the detected current signal Io is detected at any time. I am making a comparison with.

When the detected current signal Io is smaller than the output frequency rise stop current level Is (Io <Is), the compressor is operated at the target output frequency.

When the detected current signal Io is smaller than the output frequency falling current level Id and the detected current signal Io is the output frequency rising stop current level Is or more (Id> Io ≧ I)
s), stopping the frequency from rising from the output frequency at that time.

When the detected current signal Io is smaller than the output frequency stop current level It and the detected current signal Io is equal to or higher than the output frequency falling current level Id (It> Io ≧ Id),
The output frequency is decreased until the detected current signal Io becomes smaller than the output frequency decreasing current level Id (Io <Id).

Further, when the detected current signal Io becomes equal to or higher than the output frequency stop current level It (It≤Io), the generation of the output frequency is stopped.

By controlling the output frequency as described above, an overcurrent flows through the inverter device and the compressor when the condensation pressure rises and the load increases when the outside air temperature rises during cooling, for example. Prevent.

[0012]

However, in the above-mentioned prior art, when the operation is started when the compressor is in the locked state, as shown in FIG.
As indicated by the curve L0, the inverter input current rapidly increases, and the detected current signal Io rapidly increases. The locked state is a state in which the rotor inside the compressor is constrained and cannot rotate.

In FIG. 8, the detected current signal Io is It≤
When it becomes Io, the generation of the output frequency is stopped, but since the detected current signal Io becomes the output frequency falling current level Id and the output frequency rising stop current level Is before reaching the output frequency stopping current level It, the output is stopped. The frequency is controlled to stop or rise.

Therefore, the inverter device detects the detected current signal Io even though the compressor is not operating normally.
Continues to output the output frequency that satisfies Id> Io ≧ Is, and the drive current continues to flow through the compressor, which causes a problem that the compressor overheats.

The present invention has been made in order to solve the above-mentioned problems. When the compressor is started, an abnormality of the compressor is detected promptly and the operation is stopped, so that no unnecessary current is continuously supplied. In addition, it is an object of the present invention to provide an air conditioner capable of preventing abnormal overheating of a compressor and preventing burnout of a motor winding in the compressor and damage to other components.

[0016]

Therefore, the present invention provides a load reducing means for stopping the generation of the inverter frequency, or for decreasing the output frequency, or for stopping the increase of the output frequency depending on the level of the inverter input current. An air conditioner including a compressor driven by the inverter device, wherein only the generation stop current level of the inverter output frequency is valid at the time of starting the compressor.

Further, according to the present invention, preferably, when the compressor in the inverter device is started, the frequency is forcibly increased to a predetermined frequency.

At the time of starting the compressor, only the generation stop current level of the inverter output frequency is made effective and once raised to a predetermined frequency. Alternatively, at the time of starting the compressor, only the current level for stopping the generation of the inverter output frequency, which is provided separately from the generation stop current level of the inverter output frequency, is valid within a predetermined time.

[0019]

In such an inverter device, the abnormality of the compressor at the time of starting can be surely detected, and the overheating of the compressor can be prevented without continuing the useless current flow.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the air conditioner of the present invention will be described in detail below with reference to the accompanying drawings. However, the first and second embodiments described below are preferably applied to the inverter device of FIG.

Embodiment 1 FIG. 1 shows the relationship between the output frequency and the detected current value in the preferred embodiment 1 of the air conditioner of the present invention (when the target output frequency is equal to or higher than the predetermined frequency Ft), and FIG. The relationship between the output frequency and the detected current value in the preferred embodiment 1 of the air conditioner of the invention (when the target output frequency is less than the predetermined frequency Ft) is shown.

The first embodiment will be described with reference to FIGS. 1 and 4.

In FIG. 4, the operation is started (step S
1) If the target output frequency ≧ the predetermined frequency Ft, the output frequency rises from the start of the compressor (step S2), and the output frequency generation stop current level is maintained until the output frequency reaches Ft. Only It is validated, and the detected current signal Io is only compared with the generation stop current level It (steps S3 and S4).

That is, when the compressor is in the locked state, the inverter input current sharply increases as the output frequency increases, and as shown by the curve L1 in FIG.
Before the output frequency reaches the predetermined frequency Ft, the detected current signal Io reaches the output frequency generation stop current level It,
The generation of the output frequency is stopped and the compressor is stopped (steps S4 and S14).

On the other hand, as shown by the curve L2 in FIG. 1, when the compressor is normal, the output frequency is the predetermined frequency F.
Even when t is reached, the detected current signal Io is generated at the stop current level I
Since it is less than t (steps S3 and S5), the operation is continued, and after the output frequency reaches the predetermined frequency Ft, the detected current signal Io, the output frequency falling current level Id, and the output frequency rising stop current level Is are output. Also starts to be compared (steps S6 to S7), and the output frequency is controlled so that an overcurrent does not flow (steps S10, S11,
S12). That is, when the target frequency matches the output frequency, the frequency is held (S8, S12), and when the target frequency does not match the output frequency, the frequency is increased or decreased (steps S9, S10, S11).

Further, unlike the case of FIG. 1, as shown in FIG. 2, when the target output frequency is lower than the predetermined frequency Ft, the target output frequency is temporarily raised to the predetermined frequency Ft when the compressor is started (step S2). , S3).

As a result, until the target output frequency reaches the predetermined frequency Ft, only the generation stop current level It of the output frequency is made valid as in the case of the target output frequency ≧ the predetermined frequency Ft in FIG. 1 (step S3). ), The detected current signal Io is only compared with the generation stop current level It of the output frequency (step S4).

On the other hand, after the target output frequency reaches Ft in FIG. 2, as shown by the curve L4 in FIG. 2, the detected current signal Io, the output frequency falling current level Id, and the output frequency rising stop current level are output. The comparison with both Is is also started, and the output frequency is lowered to the target output frequency.

Also in this case, when the compressor is in the locked state, the detected current signal Io reaches the generation stop current level It of the output frequency before the output frequency reaches Ft, as shown by the curve L3 in FIG. Reaching, the generation of the output frequency is stopped, and the compressor is stopped (steps S4 and S14).

Second Embodiment A second embodiment will be described with reference to FIGS. 3 and 5.

Within a certain period of time T (step P2) from the start of the compressor (step P1), a second output frequency stop current level Itt is provided separately from the normal inverter output frequency stop current level Itt. Only valid and
The detected current signal Io is only compared with the generation stop current level Itt of the second output frequency (step P3).

After a lapse of a fixed time T from the start (step P
2) starts the comparison between the detected current signal Io and three of the normal inverter output frequency generation stop current level It, output frequency falling current level Id, and output frequency rising stop current level Is (steps P4 and P5). , P6), and the output frequency is controlled so that an overcurrent does not flow (steps P9, P10, P11).

Also in this case, as shown by the curve L5 in FIG. 3, when the compressor is in the locked state, the inverter input current sharply increases as the output frequency rises, and before the fixed time T elapses. The detected current signal Io reaches the second output frequency generation stop level Itt, stops the output frequency generation, and stops the compressor (steps P2, P3, P1).
3).

As described above, in the embodiment of the present invention, the load reducing means is used to stop the generation of the inverter frequency or decrease the output frequency depending on the level of the inverter input current.
Alternatively, in an air conditioner equipped with a compressor driven by an inverter device that is designed to stop the rise of the output frequency, only the generation stop current level of the inverter output frequency is valid when the compressor is started. . At the time of starting the compressor in this inverter device, the frequency is forcibly increased to a predetermined frequency. Alternatively, at the time of starting the compressor, only the generation stop current level of the inverter output frequency provided separately from the current level is valid for a predetermined time.

As described above, according to the present invention, when the compressor is started, the abnormality of the compressor is detected promptly and the operation is stopped. Therefore, it is possible to prevent abnormal overheating of the compressor and prevent burnout of the motor winding in the compressor and damage to other components.

[0035]

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an output frequency and a detected current value (when a target output frequency is equal to or higher than a predetermined frequency Ft) in a first preferred embodiment of an air conditioner of the present invention.

FIG. 2 is a diagram showing a relationship between an output frequency and a detected current value (when the target output frequency is less than a predetermined frequency Ft) in the preferred embodiment 1 of the air conditioner of the present invention.

FIG. 3 is a diagram showing a relationship between an output frequency and a detected current value in a second preferred embodiment of the air conditioner of the present invention.

FIG. 4 is a flowchart showing the first embodiment.

FIG. 5 is a flowchart showing a second embodiment.

FIG. 6 is a diagram showing a configuration of a general inverter device.

FIG. 7 is a diagram showing an output frequency and a detected current value in a conventional air conditioner.

FIG. 8 shows conventional output frequency and detected current value when the compressor is in a locked state.

[Explanation of symbols]

 3 Compressor 6 Current detector Itt Generation stop current level of second output frequency Ft Predetermined frequency Io Detection current signal Id Output frequency falling current level Is Output frequency rising stopping current level

Claims (2)

[Claims] 1. A compressor driven by an inverter device, as load reducing means, which stops generation of an inverter frequency, lowers an output frequency, or stops an increase of an output frequency depending on a level of an inverter input current. An air conditioner comprising: an air conditioner, wherein only the generation stop current level of the inverter output frequency is valid when the compressor is started. 2. The air conditioner according to claim 1, wherein when the compressor in the inverter device is started, the frequency is forcibly increased to a predetermined frequency.